1. Technical Field
The present invention relates to an electrophotographic image forming apparatus and an image forming system including the electrophotographic image forming apparatus. In particular, the present invention relates to an image forming apparatus and an image forming system, by which a toner image is formed on paper having a surface with concavities and convexities, such as embossed paper.
2. Description of Related Arts
In an image forming apparatus such as an electrophotographic printer or a copying machine, a toner image is formed on an image support such as a photoreceptor, and the formed toner image is transferred onto paper and then fused by heating and pressurization, to thereby obtain the paper on which the toner image is formed.
In recent years, the range of uses of copying machines and printers has been increased, and not only plain paper having a smooth surface but also paper with various kinds of paper quality, including embossed paper having a surface subjected to embossment, has been used. Paper having a surface with prominent concavities and convexities, such as embossed paper, has a problem that a toner transfer property becomes insufficient in concave parts, and the uniformity of an image is deteriorated.
Against such a problem, image forming apparatuses disclosed in Japanese Patent Application Laid-Open No. 2006-267486 (paragraphs 0003 to 0004) and Japanese Patent Application Laid-Open No. 2012-128229 are intended to be improved in transfer property for paper having a surface with prominent concavities and convexities by increasing the transfer pressure of a secondary transfer roller on an intermediate transfer belt.
However, the transfer pressure is increased or decreased by increasing or decreasing a load on the secondary transfer roller in the technologies of the patent literatures described above. Such a configuration in which transfer pressure is increased or decreased by a load is a simple configuration. However, the configuration has had a problem that the variable range of the transfer pressure is narrow, resulting in insufficient improvement in transfer property.
The present invention is achieved in view of the circumstances described above. An object of the present invention is to provide an image forming apparatus capable of improving the transfer property of paper with concavities and convexities, such as embossed paper.